This invention relates to a conveyor for sheet-shaped workpieces which has a switch and feeds optionally two additional conveyors with workpieces fed to it from a first conveyor, in particular bags of thermoplastic material which are produced one after the other by a bag welding machine.
From German Pat. No. 2,229,286, German published application (Offenlegunschrift) No. 2,330,614 and German Patent (Auslegeschrift) No. 2,559,138, devices of this type are known in which the switch is developed as a tongue swingable about its one end, its free end being settable alternately to one or other of the inputs of two further conveyors, so that a workpiece which is fed to the end adjacent the swivel point of the tongue can be fed optionally to a selected one of the two further conveyors.
Devices of this type serve to divide a sequence of workpieces, particularly bags produced in rapid succession one after the other in a bag welding machine, into two series of workpieces by alternately conducting said workpieces to the two further conveyors, the distances between the successive workpieces in the two series of workpieces being then greater than the length of one workpiece, so that by reducing these distances the speed of conveyance of the workpieces can be substantially reduced. This is of importance in particular when the sheet-shaped workpieces are to be stacked to form flat piles.
Specifically, if a rapid sequence of sheet-shaped workpieces, for instance bags of thermoplastic material welded in a welding machine are stacked, the individual workpieces are thrown with relatively high speed against a stop upon their stacking and thereby suddenly decelerated. Due to the sudden deceleration, the rear parts of the workpiece push themselves over the front parts so that a dependable stacking is not possible with high speeds of delivery of the sheet-shaped workpieces.
The known switches provide some help in meeting the stacking problem, since the speed of conveyance of the sheet-shaped workpieces can be substantially reduced in the two further conveyors; thus, proper stacking is made possible even in case of rapid travel of the sheet-shaped workpieces in the first conveyor.
The known switches which operate with a tongue which can be swung in and out are, however, not suitable for the purpose of deflecting workpieces which are fed in very rapid sequence, since actuation of the switches causes increasing difficulties when the speed of succession of workpieces is increased.